The subject matter disclosed herein relates generally to imaging systems, and more particularly to methods and systems for enhancing non-collected energy signals, which provides a location of an event and reduce a need for a low noise hardware circuitry.
Conventional radiation detectors receive one or more photons during an imaging session representing at least one event. A collected energy signal represents a signal created by a collecting anode in response to absorption of a photon at the voxel under the collecting anode, which represents an event collected by the radiation detector. Non-collected energy signals represent signals created by adjacent anodes that are above voxels that do not absorb the photon but are adjacent to the voxel that absorbs the photon, which is under the collecting anode. The non-collected energy signals are used to identify a position of the photon and/or event within the absorbing voxel or pixel to which may also be referred to hereby as collecting anode. Similarly, the non-absorbing voxels or pixels may also be referred to hereby as non-collecting anodes. A shaper circuit is a band-pass filter designed to improve the Signal-to-Noise Ratio (SNR) of the collecting and non-collecting signals and is utilized to conform the non-collected energy signals to a standard shape. The shaper circuit may have a peaking time (integration time) of 250 nanoseconds.
However, the non-collected energy signals are significantly smaller and/or weaker relative to the collected energy signal. The non-collected energy signals are conventionally narrow pulses that have a 30-60 nanosecond rise time and a duration time of about 50-100 ns. Also, the frequencies of the non-collected energy signals are higher relative to the collected energy signal. Based on the peaking time of the shaper circuit, which is selected for optimal SNR of the collected signal and may be 250 ns, the narrow (50-100 ns) transient non-collected energy signals are suppressed by the relatively long peaking time of the shaper circuit. Additionally, to acquire the non-collected energy signals, a low noise application specific integrated circuit is needed. For example, the low noise is needed because the signal to noise ratio of the non-collected energy signals are very poor, which may result in error. Additionally, the non-collected energy signals are utilized to determine a location of the event within the collecting anode. However, due to the suppression by the shaper circuit of the non-collected energy signals, the location of the event is difficult to calculate.